As an example of related art, FIG. 12 shows a block chart for explaining a system configuration of an optical communication apparatus and its communication method and a recording medium in which its control method is described in Japanese Unexamined Published Patent Publication HEI 11-98151 for example.
In FIG. 12, the optical communication apparatus includes a station equipment 111 and a subscriber's equipment 113. An external workstation 112 is connected to the station equipment 111, and a terminal 114 is connected to the subscriber's equipment 113.
The station equipment 111 includes a function of allowing changing bands dynamically. In a PON system, an excess band between the subscriber's equipment 113 and the station equipment 111 excluding band assurance service is shared among a plurality of subscribers subscribing to band non-assurance type service by using the function of the station equipment 111.
The subscriber's equipment 113 includes a PDS (Passive Double Star) terminating unit 131 for terminating an interface with the station equipment 111 facing to the subscriber's equipment 113, a terminal interface terminating unit 133 for terminating the band non-assurance type service in a user side, a memory 132 for performing format conversion between the PDS terminating unit 131 and the terminal interface terminating unit 133 and storing packet data, and a memory control unit 134 for measuring data accumulation volume in the memory 132 and notifying the PDS terminating unit 131 of transmission request when a signal is needed to be sent to the station equipment 111 side by opening the PDS terminating unit 131.
The station equipment 111 includes a PDS terminating unit 121 for terminating an interface with the subscriber's equipment 113 facing to the station equipment 111, a control unit 125 for terminating control information from the external workstation 112 and distributing necessary control information to each of function blocks in the equipment, a subscriber's information accumulating unit 124 for accumulating information on a subscriber who has applied to use a shard band in the control information from the control unit 125, a packet analyzing unit 123 for receiving subscriber's information from the subscriber's information accumulating unit 124 and sending a subscriber's ID and a polling instruction to the PDS terminating unit 121 and a time-division switch (TSW: TIME DIVISION SWITCH) 122.
When the packet analyzing unit 123 has transmitted the subscriber's ID and the polling instruction to the PDS terminating unit 121, the packet analyzing unit 123 receives transmission request 151 and a subscriber's ID from the relevant subscriber's station 113. When the packet analyzing unit 123 has received the transmission request, the packet analyzing unit 123 sends the relevant subscriber's equipment 113 a transmission permission signal 152 for upstream shared queuing which is shared by using the above-stated function, and receives a packet signal from the subscriber's equipment 113. Further, the packet analyzing unit 123 analyzes a packet length signal described in a packet overhead (LLC part) in a first packet signal from the subscriber's equipment 113, determines time of occupancy by the relevant subscriber's equipment based on packet length, sends the transmission permission signal 152 to the subscriber's equipment 113 only for the time of occupancy, and receives the packet signal from the subscriber's equipment 113.
As stated, the above-stated related art has adopted a method that when an OLT (OPTICAL LINE TERMINATION) as the station equipment 111 allocates a transmission band for an upstream direction to ONUs (OPTICAL NETWORK UNIT) which are a plurality of subscriber's equipments 113, the OLT sends subscriber's ID information and polling instruction information to an arbitrary ONU and receives transmission request information and the subscriber's ID information from the relevant subscriber's equipment 113, and further when the OLT has received the transmission request information, the OLT sends a transmission permission signal to the relevant subscriber's equipment 113 and receives the packet signal from the relevant subscriber's equipment 113. Further, the packet analyzing unit in the OLT has adopted a method of analyzing the packet length signal described in the packet overhead (LLC part) in the first packet signal from the subscriber's equipment 113, determining the time of occupancy by the relevant subscriber's equipment 113 based on the packet length, sending the transmission permission signal to the subscriber's equipment 113 only for the time of occupancy, and receiving the packet signal from the relevant subscriber's equipment 113. Therefore, it has been necessary that the OLT has complex function of controlling processing and function of analyzing a packet.
This invention aims at performing packet communication in a simplified sending and receiving method by sequentially allocating transmission permission of a packet on an upstream transmission line by the OLT to the plurality of ONUs registered.